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VISH&CHIPZ check out the Club of Amsterdam NanoWater Conference
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by Mathijs van Zutphen & John Grüter 01 Nanotechnology

Nanotechnology is not some abstract sci-fi future fantasy. Nanotechnology is simply engineering on a scale slightly smaller than usual, and it can provide simple and useful solutions to very real problems that concern all inhabitants of this planet. One of the areas where nanotech can realize some breakthrough technical applications in the near future is the production of clean water, a scarce commodity already, water shortage is set to produce pressing problems in the near future. On this conference it became obvious however that solutions are at hand; effective, cheap, and available as we speak.

On Monday September 30, 2004, The Club of Amsterdam and Cientifica together hosted the first international conference on nanotechnology and water “NanoWater”, at the RAI Congress Center in Amsterdam. Nanotechnology and water, an unlikely combination? Not really. In fact most of the technology presented at the conference can be defined as a solution to the following assignment: construct a really fine-grained way to sieve water.

Water is the essence of life. Most water on this planet (>95%) is seawater. Most of the drinkable fresh water is frozen on the North and South Poles, and much of the remaining available fresh water is polluted or simply in the wrong place. 75% of global precipitation occurs in areas containing less then a third of the world population.

With over 20% of the world's population having no access to safe drinking water, there is a shortage of clean fresh water now, and as developing countries raise their standard of living, this shortage will increase. Global water consumption, doubling every 20 years, is increasing much faster than the population. So if you find a smart (and cheap) way to sieve out anything from micro-organisms like bacteria and viruses to salt ions, you solve a lot of problems for a great many people, and you can make a lot of money in the process. Research into nanotechnology is receiving significant government subsidies in the US and Europe, and the total global market for clean, drinkable water is an estimated 400 billion dollars annually.

This is the theme of the day: nano filtration to clean up water. There are several competing methods for filtering water. Clean water is expensive in the third world, where, in real terms, people actually pay more money for clean water than citizens of developed countries like the USA. One of the bleak ironies of our modern world is that an essential product, virtually free to us rich citizens, is very expensive for the poor of the world. They pay up to 25% of their real income to have access to clean water.

The first speaker is Kevin McGovern of McGovern Capital LLC. Mr. McGovern explains how his investment firm is trying to spearhead the nano revolution. One of his ventures, KX Industries, is producing nano-scale filters that will filter out items as small as bacteria and viruses, for the specific purpose of eradicating waterborne disease, one of the main killers in developing countries. The product is cheap, and effective; KX Industries has actually received an FDA approval for its filters as an antiseptic. It seems that the poorest, most destitute regions of our world will benefit from nanotech's impact first. Are local conditions in developing countries changing their role from daunting problems to innovation drivers? “In some cases, Yes”, replies McGovern, who sees a huge market for KX Industries' products in developing countries. The nano filters by companies like KX Industries are very likely to change that, by providing abundant, cheap water.

One method is purely mechanical, meaning that a filter with cavities (“pores”) smaller than the undesirable particles can extract those. Aquamarijn Research BV, a Dutch firm, uses semiconductor production technology, where patterns are etched into thin wavers of silicon, to make filters. The pores of these filters are small enough to sieve out most particles and bacteria, but too large to extract viruses and synthetic pollutants like pesticides, but the development look promising.

Another way to filter water is by reversing the naturally occurring process called ‘osmosis'. Osmosis occurs when a concentrated solution, a fluid like water with a large amount of other atoms or molecules floating around in it, is separated from a less concentrated solution (less atoms and molecules) by a semi-permeable membrane. Nature has a tendency towards equilibrium, so water is drawn through the membrane towards the side with the higher concentration. This reduces the difference in concentration between the two sides of the membrane. Reverse osmosis is the process whereby pressure is applied to a concentrated solution (dirty water), forcing the fluid through a very fine membrane, resulting in a (virtually) pure fluid. The pores in these membranes are so small that reverse osmosis can be used for desalination, i.e. turning seawater into drinking water, by taking out the salt.

Reverse osmosis is slow and expensive, since applying the pressure requires large amounts of energy. Professor Raphael Semiat, Grand Water Research Institute of the Israel Institute of Technology, explains that significant cost reductions are being achieved in his research department. The latest desalination plant (in Ashkelon, Israel) produces drinking water from the Mediterranean basin at a cost of 50 dollar cents per cubic meter (1000 liter).

It is also possible to use osmosis as a process of filtering polluted water. The US military has a plastic bag containing a sucrose solution separated from the outside world with a membrane. When this bag is submerged into any quality of water after 18 hours the concentrated solution in the bag will draw about 2 liters of clean water through the membrane. Since osmosis is only effective when you start from a concentrated solution, the end product is lemonade, not water, which is not always what you want. However, for military purposes (or camping and trekking) this is ideal since the process can provide a nutritional broth. The challenge to use osmosis to provide pure water is being met by the British research organization NanoMagnetics, which produces small magnetic particles encapsulated by natural enzymes that set the same osmotic process in motion, but in the end all particles can be taken out from the fluid by applying a simple magnetic field. Elegant and effective, NanoMagnetics now faces the task of up-scaling the production of these Nanomagnets.

The effectiveness of filters is by and large a function of the size of the pores. Smaller holes mean better filtration. But that is not the only possible solution. Many particles, organic and synthetic, are sensitive to an electrical charge. Fred Tepper of the US company Argonide explains how his company has created a filter comprising oxidized aluminum nanofibers, on a glass fiber substrate. These alumina fibers are positively charged, which enables them to filter bio-organisms such as bacteria and viruses from the water flow. Even though the pores in this filter are relatively large, the end result is extremely effective, because the process provides a much higher flow rate than traditional membranes. The filter retains up to 99.999% of viruses, is in production as we speak, and can be used to clean water by applying muscle force. No extra energy needed, ideal for rural contexts.

Filters based on nano-technology are a very practical application, providing a low-cost – less than $0,25 per liter – solution. As more people in the third world die for lack of clean water than from any other cause, nano-technology can be said to provide genuine benefit to mankind. Not just in the third world, but also in the developed world many situations exist where this type of technology can make a substantial difference.

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